U.S. patent application number 16/753282 was filed with the patent office on 2020-10-22 for automatically select guard interval value.
The applicant listed for this patent is Hewlett Packard Enterprise Development LP. Invention is credited to Jianpo HAN, Xuguang JIA, Guangzhi RAN, Qiang ZHOU.
Application Number | 20200336349 16/753282 |
Document ID | / |
Family ID | 1000004968428 |
Filed Date | 2020-10-22 |
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United States Patent
Application |
20200336349 |
Kind Code |
A1 |
ZHOU; Qiang ; et
al. |
October 22, 2020 |
AUTOMATICALLY SELECT GUARD INTERVAL VALUE
Abstract
In one example in accordance with the present disclosure, a
device may include a processor to detect a distance between a first
location of the device and a second location of a peer device,
automatically select one value for GI from at least two available
values based on the detected distance, and update the value of GI
using the selected value. A method may include detecting a distance
between a first location of the AP and a second location of a peer
device, selecting one value for GI from at least two available
values based on the detected distance, and updating the value of GI
using the selected value.
Inventors: |
ZHOU; Qiang; (Santa Clara,
CA) ; JIA; Xuguang; (Beijing, CN) ; HAN;
Jianpo; (Beijing, CN) ; RAN; Guangzhi;
(Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hewlett Packard Enterprise Development LP |
Houston |
TX |
US |
|
|
Family ID: |
1000004968428 |
Appl. No.: |
16/753282 |
Filed: |
October 23, 2017 |
PCT Filed: |
October 23, 2017 |
PCT NO: |
PCT/CN2017/107322 |
371 Date: |
April 2, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 27/2646 20130101;
H04W 4/70 20180201; H04W 64/006 20130101; H04W 84/12 20130101; H04L
27/2607 20130101 |
International
Class: |
H04L 27/26 20060101
H04L027/26; H04W 64/00 20060101 H04W064/00; H04W 4/70 20060101
H04W004/70 |
Claims
1. A device comprising a processor to: detect a distance between a
first location of the device and a second location of a peer
device; automatically select one value for Guard Interval (GI) from
at least two available values based on the detected distance; and
update the value of GI using the selected value.
2. The device of claim 1, wherein the distance between the device
and a peer device is detected by measuring a transmission time of a
packet transmitted between the device and the peer device.
3. The device of claim 2, wherein the selected value for GI is not
less than a difference between the measured transmission time and a
pre-determined longest transmission time.
4. The device of claim 2, wherein the selected value for GI is no
less than a transmission time associated with the distance times a
ratio of (1) difference between a longest path and a shortest path,
and (2) the shortest path.
5. The device of claim 1, wherein the at least two available values
include 0.8 .mu.s, 1.6 .mu.s and 3.2 .mu.s when the device is
compliant with the IEEE 802.11ax standard, and 0.4 .mu.s and 0.8
.mu.s when the device is compliant with the IEEE 802.11n
standard.
6. The device of claim 1, wherein the processor is further to:
notify the peer device to update the value of GI using the selected
value.
7. The device of claim 1, wherein the device comprises an access
point (AP), and the peer device comprises a mobile device or
another AP.
8. A method comprising: detecting, by a processor of an access
point (AP), a distance between a first location of the AP and a
second location of a peer device; automatically selecting, by the
processor, one value for Guard Interval (GI) from at least two
available values based on the detected distance; and updating, by
the processor, the value of GI using the selected value.
9. The method of claim 8, wherein the distance between the device
and a peer device is detected by measuring a transmission time of a
packet transmitted between the device and the peer device.
10. The method of claim 9, wherein the selected value for GI is not
less than a difference between the measured transmission time and a
pre-determined longest transmission time.
11. The method of claim 9, wherein the selected value for GI is no
less than a transmission time associated with the distance times a
ratio of (1) difference between a longest path and a shortest path,
and (2) the shortest path.
12. The method of claim 8, wherein the at least two available
values include 0.8 .mu.s, 1.6 .mu.s and 3.2 .mu.s when the AP is
compliant with the IEEE 802.11ax standard, and the at least two
available values include 0.4 .mu.s and 0.8 .mu.s when the AP is
compliant with the IEEE 802.11n standard.
13. The method of claim 8, further comprising: notifying, by the
processor, the peer device to update the value of GI using the
selected value.
14. A non-transitory computer readable storage medium storing
instructions that, when executed by a processor of an access point
(AP), causes the processor to: detect a distance between a first
location of the AP and a second location of a peer device;
automatically select one value for Guard Interval (GI) from at
least two available values based on the detected distance; and
update the value of GI using the selected value.
15. The non-transitory computer readable storage medium of claim
14, further storing instructions that, when executed by the
processor, causes the processor to: notify a peer device to update
the guard interval using the selected value.
Description
BACKGROUND
[0001] Guard Interval (GI) used in IEEE 802.11 Standard is provided
to ensure that distinct transmissions in a wireless local area
network (WLAN) do not interfere with one another. In some cases,
the interference between the distinct transmissions cannot be
constantly prevented by GI with a fixed value, such that the Radio
Frequency (RF) link quality in the wireless system is difficult to
be maintained at a proper ratio.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] FIG. 1 is a block diagram illustrating an example wireless
system including a wireless device capable of automatically
selecting the value of GI according to the present disclosure;
[0003] FIG. 2 is a diagram illustrating an example model for
automatically selecting the value of GI according to present
disclosure;
[0004] FIG. 3 is a diagram illustrating an example case of longest
path in the model shown in FIG. 2 according to present
disclosure;
[0005] FIG. 4 is a diagram illustrating an example of automatically
selecting the value of GI for meeting the change of the distance
according to the present disclosure;
[0006] FIG. 5 is a diagram illustrating another example of
automatically selecting the value of GI for meeting the change of
the distance according to the present disclosure;
[0007] FIG. 6 is a flow chart illustrating an example method for
improving link quality according to present disclosure;
[0008] FIG. 7 is a flow chart illustrating another example method
for improving link quality according to present disclosure;
[0009] FIG. 8 is a schematic illustrating example components for
implementing the device shown in FIG. 1 according to present
disclosure; and
[0010] FIG. 9 is a schematic illustrating example components for
implementing the device shown in FIG. 1 according to present
disclosure.
DETAILED DESCRIPTION
[0011] In order to ensure that distinct transmissions in the
wireless local area network (WLAN) do not interfere with one
another, the interference due to multipath reflections generated by
distinct transmissions is desired to fall into GI in a high ratio.
The portion of interference falling into GI can be prevented from
affecting Orthogonal Frequency Division Multiplexing (OFDM) or
Orthogonal Frequency Division Multiple Access (OFDMA) symbols
outside GI. As the ratio of the interference falling into GI gets
higher, the radio frequency (RF) link quality in the WLAN is
better.
[0012] The ratio of the interference falling into GI is influenced
by not only the value of GI, but also the distance among the
wireless devices or the length of a transmission path among the
wireless devices. If the value of GI is configured to be fixed, the
interference falling into GI cannot be ensured to be a proper
ratio, when the distance among wireless devices or the length of a
transmission path among the wireless devices changes, due to the
movement of the wireless device.
[0013] For example, in IEEE 802.11ax standard, three available
values are provided for GI, e.g., 0.8 .mu.s, 1.6 .mu.s, and 3.2
.mu.s, but only one of the three values can be chosen and manually
configured to be the fixed value of GI. However, when the wireless
device moves such that the distance among the wireless devices or
the length of a transmission path among the wireless devices
changes, the value configured as the fixed value of GI cannot
change without manually reconfiguring, and it is possible for the
interference to fall outside GI in a higher ratio with respect to a
pre-expected ratio, such that the symbols outside GI may be
affected by the interference.
[0014] Similarly, in IEEE 802.11n standard, two available values
are provided for GI, e.g., 0.4 .mu.s and 0.8 .mu.s, and the value
of GI can be manually configured by one of the two values, such
that it is also possible for the interference to mostly fall
outside GI and affect the symbols outside GI, when the distance
among the wireless devices or the length of a transmission path
among the wireless devices changes.
[0015] Although the fixed value of GI can be manually reconfigured,
it is difficult for the manual reconfiguration to keep up with the
change of the distance among the wireless devices or the length of
a transmission path among the wireless devices, especially for an
outdoor deployment in which the wireless device moves frequently
and/or moves at a high speed.
[0016] Accordingly, in the examples herein, the distance among
wireless devices or the length of a transmission path among the
wireless devices can be detected or estimated. The value of GI can
be automatically tunable according to the detected or estimated
distance among wireless devices, or the length of a transmission
path among the wireless devices. That is, the value of G may be
automatically tuned among a plurality of standard specified GI
values (e.g., among the three values 0.8 .mu.s, 1.6 .mu.s and 32
.mu.s for IEEE 802.11ax standard, or between the two values 0.4
.mu.s and 0.8 .mu.s for IEEE 802.11n standard) based on the change
of the distance among the wireless devices or the length of a
transmission path among the wireless devices.
[0017] In other words, the tuning of the value of GI may not be
limited by the manual configuration and may be released real-time
to meet the distance among wireless devices or the length of a
transmission path among the wireless devices.
[0018] When providing a fixed value for GI, the interference
falling into GI can be maintained at a proper ratio, even if the
distance among the wireless devices or the length of a transmission
path among the wireless devices changes, whenever the change is
frequent and/or at a high speed. Moreover, the transmission rate in
the WLAN cannot be compromised due to a large value of GI being
configured.
[0019] In one example, a device comprising a processor to detect a
distance between a first location of the device and a second
location of a peer device, to automatically select one of at least
two values available to GI based on the detected distance, and to
update the value of GI using the selected value. Further, processor
is to notify the peer device to update the value of GI using the
selected value, or the peer device may synchronously self-update
the value of G. Both of the device and the peer device may be
wireless devices, e.g. the device may be an access point (AP), and
the peer device may be a mobile device or another AP.
[0020] In another example, a method for improving link quality
comprises detecting, by a processor of an AP, a distance between a
first location of the AP and a second location of a peer device.
The method comprises automatically selecting, by the processor, one
value for GI from at least two available values based on the
detected distance. And, the method comprises updating, by the
processor, the value of GI using the selected value. Further, the
method may comprise notifying, by the processor, the peer device to
update the value of GI using the selected value. Instead of
notifying the peer device to update the value of GI using the
selected value, the peer device may synchronously self-update the
value of GI.
[0021] In another example, a non-transitory computer readable
storage medium stores instructions that, when executed by a
processor of an AP, causes the processor to detect a distance
between a first location of the AP and a second location of a peer
device, to automatically select one value for GI from at least two
available values based on the detected distance, and to update the
value of GI using the selected value. Further, the non-transitory
computer readable storage medium may store instructions that, when
executed by the processor, causes the processor to notify a peer
device to update the guard interval using the selected value, or
the peer device may synchronously self-update the value of GI.
[0022] As used herein, a "network device" generally includes a
device that is adapted to transmit and/or receive signaling and to
process information within such signaling such as a station (e.g.,
any data processing equipment such as a computer, cellular phone,
personal digital assistant, tablet devices, etc.), an access point,
data transfer devices (such as network switches, routers,
controllers, etc.) or the like. As used herein, an "access point"
(AP) generally refers to receiving points for any known or
convenient wireless access technology which may later become known.
Specifically, the term AP is not intended to be limited to IEEE
802.11-based APs. APs generally function as an electronic device
that is adapted to allow wireless devices to connect to a wired
network via various communications standards.
[0023] It is appreciated that examples described herein below may
include various components and features. Some of the components and
features may be removed and/or modified without departing from a
scope of the device, method and non-transitory computer readable
storage medium for improving link quality by automatically tuning
the value of GI. It is also appreciated that, in the following
description, numerous specific details are set forth to provide a
thorough understanding of the examples. However, it is appreciated
that the examples may be practiced without limitations to these
specific details. In other instances, well known methods and
structures may not be described in detail to avoid unnecessarily
obscuring the description of the examples. Also, the examples may
be used in combination with each other.
[0024] Reference in the specification to "an example" or similar
language means that a particular feature, structure, or
characteristic described in connection with the example is included
in at least one example, but not necessarily in other examples. The
various instances of the phrase "in one example" or similar phrases
in various places in the specification are not necessarily all
referring to the same example. As used herein, a component is a
combination of hardware and software executing on that hardware to
provide a given functionality.
[0025] FIG. 1 is a block diagram illustrating an example WLAN
including a wireless device capable of tuning the value of GI
according to the present disclosure. Referring to FIG. 1, a WLAN
includes a device 10 and at least one mobile device 20. The device
10 may be an AP or any other device capable of transmitting
wireless transmissions to and receiving wireless transmissions from
the mobile device 20. The Mobile device 20 may be a smartphone, a
mobile phone, a Personal Digital Assistant (PDA), a portable
personal computer, an AIO (all-in-one) computing device, a
notebook, a convertible or hybrid notebook, a netbook, a tablet, a
cellular device, a desktop computer, a multimedia player, an
entertainment unit, a data communication device, a portable reading
device, or any other computing device capable of transmitting and
receiving wireless transmissions. The symbols may be exchanged
between the device 10 and the at least one mobile devices 20.
[0026] The device 10 includes at least one antenna 11 that may be
coupled to a RF transceiver 12 for transmitting the wireless
transmissions to and receiving the wireless transmissions from the
mobile devices 20. The mobile device 20 also includes at least one
antennas 21 that may be coupled to a RF transceiver 22 for
transmitting the wireless transmissions to and receiving the
wireless transmissions from the device 10.
[0027] The wireless transmission transmitted and received among the
device 10 and the mobile device 20 may traverse in various radial
directions, and reflect off walls, furniture, and other objects.
Due to the reflections, multiple copies of the same wireless
transmission may arrive at a receiver, each undergoing a different
delay and attenuation--a phenomenon commonly referred to as
"multipath." which can cause the interference.
[0028] The RF transceivers 12 and 22 can transmit and receive the
wireless transmissions by utilizing GI. GI utilized by the RF
transceivers 12 and 22 is automatically tunable based on a distance
D between the device 10 and the mobile device 20, and may be
regarded as a function GI(D) 100 or 200 correlated with the
distance D.
[0029] Generally, the distance D may be the length of a path in
multipath closest to a "direct path" of the wireless transmission.
As used herein, the "direct path" of the wireless transmission may
refer to a straight line joining the mobile device 20 and the
device 10.
[0030] The device 10 may include a processor 13 capable of tuning
the value of GI utilized by the RF transceiver 12 when transmitting
and receiving wireless transmissions, according to the distance D.
The value of GI utilized by the RF transceiver 22 may be also tuned
by the processor 13, or synchronously self-updated by the mobile
device 20. The processor 13 can be a hardware component and can
execute instructions of a software component.
[0031] The processor 13 may detect or estimate the distance D
between a first location of the device 10 and a second location of
the mobile device 20 (regarded as a peer device of the device 10).
The distance D may be detected or estimated based on a time delay
or an energy loss during the wireless transmission.
[0032] For example, a Round-Trip Time (RTT) may be chosen as a time
delay for detecting or estimating the distance D.
[0033] First, the device 10 can send out a distance measure request
frame to the mobile device 20 and record the timestamp
T.sub.dreqssnd when the frame being sent out.
[0034] Second, the mobile device 20 (regarded as a peer device by
the device 10) can record the timestamp T.sub.dreqrecv when the
measure request frame from the device 10 is received, and record
the timestamp T.sub.drspsend when a measure respond frame is sent
back to the device 10. And both T.sub.dreqrecv and T.sub.drspsend
will be included in the measure respond frame.
[0035] Then, the device 10 records timestamp T.sub.drsprecv when
the measure respond frame from the mobile device 20 is received,
and extracts T.sub.dreqrecv and T.sub.drspsend from the received
measure respond frame.
[0036] Accordingly, the processor 13 may calculate a frame
transmission time T.sub.distance from equation (1) below.
T distance = ( T drsprecv - T drspsend ) + ( T drsprecv - T
drspsend ) 2 . Equation ( 1 ) ##EQU00001##
[0037] With a simple mathematic transformation, two timestamps
which are marked by a same wireless device (i.e. the device 10 or
the mobile device 20) can be put together to decouple the time
synchronization between different devices, and the above equation 1
may be transformed to be equation 2 below.
T distance = ( T drsprecv - T drspsend ) + ( T drspecv - T drspsend
) 2 . Equation ( 2 ) ##EQU00002##
[0038] Generally, as the speed of electrical wave is a constant
value, the distance D between the device 10 and the mobile device
20 may be reflected by the calculated frame transmission time
T.sub.distance.
[0039] The processor 13 may tune the value of G among at least two
available values GI.sub.1.about.GI.sub.n (n.gtoreq.2), by selecting
one value for GI from at least two available values
GI.sub.1.about.GI.sub.n, based on the detected distance D reflected
by the transmission time T.sub.distance.
[0040] Considering GI is used to protect the symbols in multi-path
transmission, the most vulnerable case for one symbol is the
difference value between the shortest path and the longest
reflection path. If the difference value between the shortest path
and the longest reflection path exceed the value of GI, GI seems
impossible to protect the symbols and its value needs to be
tuned.
[0041] As the distance D may be substantially the length of a path
in multipath closet to a "direct path" of the wireless
transmission, the detected or estimated distance D may be regarded
as the shortest path, such that the transmission time
T.sub.distance reflecting the distance D may be regarded as a
shortest transmission time in real environment.
[0042] Accordingly, the value of GI may be tuned to be not less
than a difference between the measured transmission time
T.sub.distance and a pre-determined longest transmission time
T.sub.longest. That is, the selected value for GI from the at least
two available values GI.sub.1.about.GI.sub.n is not less than a
difference between the measured transmission time T.sub.distance
and a pre-determined longest transmission time T.sub.longest.
[0043] For example, when three available values 0.8 .mu.s, 1.6
.mu.s and 3.2 .mu.s are provided for GI, as defined in the IEEE
802.11ax standard, the value of GI may be tuned as follows:
[0044] If (T.sub.longest-T.sub.distance)<0.8 .mu.s
[0045] GI=0.8 .mu.s,
[0046] Else if (T.sub.longest=T.sub.distance)<1.6 .mu.s
[0047] GI=1.6 .mu.s,
[0048] else,
[0049] GI=3.2 .mu.s.
[0050] The pre-determined longest transmission time T.sub.longest
may be obtained from experiences according to the deployment or
estimated from some mathematic models.
[0051] FIG. 2 is a diagram illustrating an example of a model for
tuning the value of GI according to present disclosure. Referring
to FIG. 2, in a created model, anyone of the device 10 and the
terminal device 20 may stand for a sender, the other one of the
device 10 and the terminal device 20 may stand for a receiver, and
a circular curve represents the signal transmission range. Between
the device 10 and the terminal device 20, there are a direct
transmission path P.sub.c and a plurality of reflection
transmission paths P.sub.a1+P.sub.b1.about.P.sub.am+P.sub.bm
(m>1).
[0052] If the difference between the reflection transmission path
P.sub.ai+P.sub.bi (1.ltoreq.i.ltoreq.m) and the direction
transmission path P.sub.c is larger than V.times.GI (V is the speed
of electromagnetic wave), i.e.
P.sub.ai+P.sub.bi-P.sub.c>V.times.GI, multi-path transmission
issue will be involved, such that the interference falls outside
GI, and the RF link quality in the wireless system will be
worse.
[0053] Accordingly, the max value of GI capable of protecting the
symbols may meet the equation (3) below.
Max(P.sub.ai+P.sub.bi-P.sub.c).ltoreq.V.times.GI. Equation (3):
[0054] As the direction transmission path P.sub.c is a shortest
transmission path, and the reflection transmission path
P.sub.ai+P.sub.bi is a longest shortest transmission path when
P.sub.si=P.sub.bi, the equation (3) may be transformed to be the
equation (4) below.
Path.sub.longest-Path.sub.shortest.ltoreq.V.times.GI. Equation
(4):
[0055] Further, as the distance D may be substantially closest to
the direct transmission path P.sub.c, i.e. the Path.sub.shortest in
the equation (4), by substituting the equation (5) below into the
equation (4), the equation (4) may be transformed to be the
equation (6) below.
T distance = Path shortest V , Equation ( 5 ) GI .gtoreq. Path
longest - Path shortest Path shortest .times. T distance . Equation
( 6 ) ##EQU00003##
[0056] Therefore, the equation (6) may be used for determining the
condition for tuning the value of GI, and the value of GI
determined according to the equation (6) is no less than a
transmission time associated with the distance times a ratio of (1)
difference between a longest path Path.sub.longest and a shortest
path Path.sub.shortest, and (2) the shortest path
Path.sub.shortest.
[0057] FIG. 3 is a diagram illustrating a case of longest path in
the model shown in FIG. 2 according to present disclosure.
Referring to FIG. 3, when the length of the section P.sub.ai equals
to the length of the section P.sub.bi, the value of the difference
between the reflection transmission path P.sub.ai+P.sub.bi and the
direction transmission path P.sub.c is largest. In the case of
P.sub.ai=P.sub.bi, the condition of RF link quality in the wireless
system is worst.
[0058] Accordingly, the equation (3) may be simplified to be the
equation (7) or (8) below.
( {square root over (2)}-1)P.sub.c.ltoreq.V.times.GI, Equation
(7):
0.4.times.P.sub.c.ltoreq.V.times.GI. Equation (8):
[0059] As the direction transmission path P.sub.c is a shortest
transmission path, and the reflection transmission path
P.sub.ai+P.sub.bi is a longest shortest transmission path when
P.sub.ai=P.sub.bi, the equations (7) and (8) may be transformed to
be the below equations (9) and (10), respectively.
( {square root over (2)}-1)Path.sub.shortest.ltoreq.V.times.GI,
Equation (9):
0.4.times.Path.sub.shortest.ltoreq.V.times.GI. Equation (10):
[0060] By substituting the equation (5) into the equations (9) and
(10), the equations (9) and (10) may be transformed to be the
equations (11) and (12), respectively.
GI .gtoreq. T distance 2 - 1 , Equation ( 11 ) GI .gtoreq. 0.4
.times. T distance . Equation ( 12 ) ##EQU00004##
[0061] Alternatively, the equation (12) may be transformed to be
the below equation (13) for configuring at least one threshold
T.sub.thres for transmission time T.sub.distance, at least two
pre-determined threshold sections may be established by the at
least one threshold T.sub.thres, and each threshold section
corresponds to one of at least two values
GI.sub.1.about.GI.sub.n.
T.sub.thres1-n=2.5.times.GI.sub.1. Equation (13):
[0062] If the measured transmission time T.sub.distance falls into
any of the at least two pre-determined threshold ranges, a
corresponding one of at least two values GI.sub.1.about.GI.sub.n
may be chosen to tune the value of GI.
[0063] For example, when three available values 0.81 .mu.s, 1.6
.mu.s and 3.2 .mu.s are provided for GI, as defined in the IEEE
802.11ax standard, two thresholds T.sub.thres1 and T.sub.thres2 can
be configured by utilizing the equation (13):
T.sub.thres1=2.5.times.0.8 .mu.s=2 .mu.s, and
T.sub.thres2=2.5.times.1.6 .mu.s=4 .mu.s.
[0064] Accordingly, there will be three threshold ranges
established by the two thresholds T.sub.thres1 and T.sub.thres2,
i.e. [0 .mu.s, 2 .mu.s), [2 .mu.s, 4 .mu.s), and [4 .mu.s,
+.infin.), and the value of GI may be tuned as follows:
[0065] If (T.sub.distance)<2 .mu.s, the transmission time
T.sub.distance falls into the section [0 .mu.s, 2 .mu.s),
GI=0.8 .mu.s,
[0066] Else if (T.sub.distance)<4 .mu.s, the transmission time
T.sub.distance falls into the section [2 .mu.s, 4 .mu.s),
GI=1.6 .mu.s,
[0067] else, the transmission time T.sub.distance falls into the
section [4 .mu.s, +.infin.),
GI=3.2 .mu.s.
[0068] After determining the selected value of GI, the processor 13
can update the value of GI, i.e. the function GI(D) 100, using the
selected value. If necessary, the processor 13 notifies the mobile
device 20 to update the value of GI, i.e. the function GI(D) 200,
using the selected value.
[0069] FIG. 4 is a diagram illustrating an example of tuning the
value of GI for meeting the change of the distance according to the
present disclosure. Referring to FIG. 4, take three available
values GI.sub.1=0.8 .mu.s, GI.sub.2=1.6 .mu.s and GI.sub.3=3.2
.mu.s for example:
[0070] During the period t1.about.t2, the transmission time
T.sub.distance falls into the section [0 .mu.s, 2 .mu.s), and the
value of GI between the symbols 30 is tuned by the processor 13 to
be GI.sub.1=0.8 .mu.s.
[0071] During the period t2.about.t3, the transmission time
T.sub.distance falls into the section [2 .mu.s, 4 .mu.s), and the
value of GI between the symbols 30 is tuned by the processor 13 to
be GI.sub.2=1.6 .mu.s.
[0072] During the period after t3, the transmission time
T.sub.distance falls into the section [4 .mu.s, +.infin.), and the
value of GI between the symbols 30 is tuned by the processor 13 to
be GI.sub.3=3.2 .mu.s.
[0073] 3 As can be seen, the value of GI may be tuned due to the
change of the distance D reflected by the transmission time
T.sub.distance.
[0074] If there are more than one mobile devices 20 included in the
wireless system, the values of GI corresponding to different mobile
devices 20 are unnecessary to be the same.
[0075] FIG. 5 is a diagram illustrating another example of tuning
the value of GI for meeting the change of the distance according to
the present disclosure. Referring to FIG. 5, take three available
values GI.sub.1=0.8 .mu.s, GI.sub.2=1.6 .mu.s and GI.sub.3=3.2
.mu.s for example:
[0076] During the period t1.about.t2, the transmission time
T.sub.distance between the device 10 and one of the mobile device
20 falls into the section [0 .mu.s, 2 .mu.s), and the value of GI
between the symbols 41 of that mobile device 20 is tuned by the
processor 13 to be GI.sub.1=0.8 .mu.s. Meanwhile, the transmission
time T.sub.distance between the device 10 and another one of the
mobile device 20 falls into the section [0 .mu.s, 2 .mu.s) also,
and the value of GI between the symbols 42 of another mobile device
20 is tuned by the processor 13 to be GI.sub.1=0.8 .mu.s.
[0077] During the period t2.about.t3, the transmission time
T.sub.distance between the device 10 and one of the mobile device
20 falls into the section [2 .mu.s, 4 .mu.s), and the value of GI
between the symbols 30 is tuned by the processor 13 to be
GI.sub.2=1.6 .mu.s. Meanwhile, the transmission time T.sub.distance
between the device 10 and another one of the mobile device 20 still
falls into the section [0 .mu.s, 2 .mu.s), and the value of GI
between the symbols 42 of another mobile device 20 is also
GI.sub.1=0.8 .mu.s and is not tuned by the processor 13.
[0078] During the period t3.about.t4, the transmission time
T.sub.distance between the device 10 and one of the mobile device
20 still falls into the section [2 .mu.s, 4 .mu.s), and the value
of GI between the symbols 30 is not tuned by the processor 13 and
maintained to be GI.sub.2=1.6 .mu.s. Meanwhile, the transmission
time T.sub.distance between the device 10 and another one of the
mobile device 20 falls into the section [2 .mu.s, 4 .mu.s), and the
value of GI between the symbols 42 of another mobile device 20 is
tuned by the processor 13 to be GI.sub.2=1.6 .mu.s.
[0079] During the period after t4, the transmission time
T.sub.distance falls into the section [4 .mu.s, +.infin.), and the
value of GI between the symbols 30 is tuned by the processor 13 to
be GI.sub.3=3.2 .mu.s. Meanwhile, the transmission time
T.sub.distance between the device 10 and another one of the mobile
device 20 still falls into the section [2 .mu.s, 4 .mu.s), and the
value of GI between the symbols 42 of another mobile device 20 is
also GI.sub.2=1.6 .mu.s and is not tuned by the processor 13.
[0080] As can be seen, the values of GIs corresponding to different
mobile devices 20 are unnecessary to be synchronized.
[0081] Alternatively, the above examples are also suitable for case
of the peer device being another AP, i.e. the mobile device 20 in
the above examples may be replaced by another AP different from the
device 10 working as an AP, and the distance between a pair of APs
may be also changeable.
[0082] FIG. 6 is a flow chart illustrating an example of a method
for improving link quality according to present disclosure.
Referring to FIG. 6:
[0083] The method 600 comprises detecting, by a processor of an AP,
a distance between a first location of the AP and a second location
of a peer device, at 601. In one example, the distance between the
device and a peer device may be detected by measuring a
transmission time among the device and the peer device.
[0084] The method 600 comprises automatically selecting, by the
processor, one value for GI from at least two available values
based on the detected distance, at 602. In one example, the
selected value for GI may be not less than a difference between the
measured transmission time and a pre-determined longest
transmission time. In another example, the selected value for GI
may meet the equation (6) mentioned above, or the selected value
for GI may be the value corresponding to one of the pre-determined
threshold section, into which the transmission time falls.
[0085] The method 600 comprises updating, by the processor, the
value of GI using the selected value, at 603. In one example, the
selected value may be one of 0.8 .mu.s, 1.6 .mu.s, 3.2 .mu.s when
the AP is compliant with the IEEE 802.11ax standard, and may be one
of 0.4 .mu.s and 0.8 .mu.s when the AP is compliant with the IEEE
802.11n standard.
[0086] FIG. 7 is a flow chart illustrating another example of a
method for improving link quality according to present disclosure.
Referring to FIG. 7:
[0087] The method 700 comprises detecting, by the processor of the
AP, a distance between a first location of the AP and a second
location of a peer device, at 701. Similarly to the method 600, the
distance between the device and a peer device may be detected by
measuring a transmission time among the device and the peer
device.
[0088] The method 700 comprises automatically selecting, by the
processor, one value for GI from at least two available values
based on the detected distance, at 702. Similarly to the method
600, the selected value for GI may be not less than a difference
between the measured transmission time and a pre-determined longest
transmission time. Instead, the selected value for GI may meet the
equation (6) mentioned above, or the selected value for GI may be
the value corresponding to one of the pre-determined threshold
section, into which the transmission time falls.
[0089] The method 700 comprises updating, by the processor, the
value of GI using the selected value, at 703. The selected value
may be one of 0.8 .mu.s, 1.6 .mu.s, 3.2 .mu.s.
[0090] The method 700 comprises notifying, by the processor, the
peer device to update the value of GI using the selected value, at
704.
[0091] FIG. 8 is a schematic illustrating an example of components
for implementing the device, i.e. device 10, shown in FIG. 1
according to present disclosure. The component 800 includes a RF
transceiver 801, a processor 802, a non-volatile or volatile memory
803 and/or a non-transitory computer readable storage medium
804.
[0092] The memory 803 stores at least two values
GI.sub.1.about.GI.sub.n available to GI, which can be read by the
RF transceiver 801. The non-transitory computer readable storage
medium 804 stores instructions excitable for the possessor 802.
[0093] The instructions include distance detecting instructions,
when executed by the processor 802, causes the processor 802 to
detect a distance between a first location of the AP and a second
location of a peer device, when executed by the processor 802.
[0094] The instructions include value selecting instructions, when
executed by the processor 802, causes the processor 802 to
automatically select one value for GI from at least two available
values based on the detected distance.
[0095] The instructions include value updating instructions, when
executed by the processor 802, causes the processor 802 to update
the value of GI using the selected value. For example, the updated
value of GI may be correctly read from the memory 803 by the RF
transceiver 801.
[0096] FIG. 9 is a schematic illustrating another example of
components for implementing the device, i.e. device 10 such as an
AP, shown in FIG. 1 according to present disclosure. The component
900 includes a RF transceiver 901, a processor 902, a non-volatile
or volatile memory 903 and/or a non-transitory computer readable
storage medium 904.
[0097] The memory 903 stores at least two values
GI.sub.1.about.GI.sub.n available to GI, which can be read by the
RF transceiver 901. The non-transitory computer readable storage
medium 904 stores instructions excitable for the possessor 902.
[0098] The instructions include distance detecting instructions,
when executed by the processor 902, causes the processor 902 to
detect a distance between a first location of the AP and a second
location of a peer device, when executed by the processor 902.
[0099] The instructions include value selecting instructions, when
executed by the processor 902, causes the processor 902 to
automatically select one value for GI from at least two available
values based on the detected distance.
[0100] The instructions include value updating instructions, when
executed by the processor 902, causes the processor 902 to update
the value of GI using the selected value. For example, the updated
value of GI may be correctly read from the memory 803 by the RF
transceiver 901.
[0101] The instructions include peer notifying instructions, when
executed by the processor 902, causes the processor 902 to notify a
peer device to update the value of GI using the selected value.
[0102] While the present disclosure has been described in
connection with certain example embodiments, it is to be understood
that the disclosure is not limited to the disclosed embodiments,
but, on the contrary, is intended to cover various modifications
and equivalent arrangements included within the spirit and scope of
the appended claims, and equivalents thereof.
* * * * *